#! /opt/alt/python33/bin/python3.3
"""Conversions to/from quoted-printable transport encoding as per RFC 1521."""
# (Dec 1991 version).
__all__ = ["encode", "decode", "encodestring", "decodestring"]
ESCAPE = b'='
MAXLINESIZE = 76
HEX = b'0123456789ABCDEF'
EMPTYSTRING = b''
try:
from binascii import a2b_qp, b2a_qp
except ImportError:
a2b_qp = None
b2a_qp = None
def needsquoting(c, quotetabs, header):
"""Decide whether a particular byte ordinal needs to be quoted.
The 'quotetabs' flag indicates whether embedded tabs and spaces should be
quoted. Note that line-ending tabs and spaces are always encoded, as per
RFC 1521.
"""
assert isinstance(c, bytes)
if c in b' \t':
return quotetabs
# if header, we have to escape _ because _ is used to escape space
if c == b'_':
return header
return c == ESCAPE or not (b' ' <= c <= b'~')
def quote(c):
"""Quote a single character."""
assert isinstance(c, bytes) and len(c)==1
c = ord(c)
return ESCAPE + bytes((HEX[c//16], HEX[c%16]))
def encode(input, output, quotetabs, header=False):
"""Read 'input', apply quoted-printable encoding, and write to 'output'.
'input' and 'output' are files with readline() and write() methods.
The 'quotetabs' flag indicates whether embedded tabs and spaces should be
quoted. Note that line-ending tabs and spaces are always encoded, as per
RFC 1521.
The 'header' flag indicates whether we are encoding spaces as _ as per
RFC 1522.
"""
if b2a_qp is not None:
data = input.read()
odata = b2a_qp(data, quotetabs=quotetabs, header=header)
output.write(odata)
return
def write(s, output=output, lineEnd=b'\n'):
# RFC 1521 requires that the line ending in a space or tab must have
# that trailing character encoded.
if s and s[-1:] in b' \t':
output.write(s[:-1] + quote(s[-1:]) + lineEnd)
elif s == b'.':
output.write(quote(s) + lineEnd)
else:
output.write(s + lineEnd)
prevline = None
while 1:
line = input.readline()
if not line:
break
outline = []
# Strip off any readline induced trailing newline
stripped = b''
if line[-1:] == b'\n':
line = line[:-1]
stripped = b'\n'
# Calculate the un-length-limited encoded line
for c in line:
c = bytes((c,))
if needsquoting(c, quotetabs, header):
c = quote(c)
if header and c == b' ':
outline.append(b'_')
else:
outline.append(c)
# First, write out the previous line
if prevline is not None:
write(prevline)
# Now see if we need any soft line breaks because of RFC-imposed
# length limitations. Then do the thisline->prevline dance.
thisline = EMPTYSTRING.join(outline)
while len(thisline) > MAXLINESIZE:
# Don't forget to include the soft line break `=' sign in the
# length calculation!
write(thisline[:MAXLINESIZE-1], lineEnd=b'=\n')
thisline = thisline[MAXLINESIZE-1:]
# Write out the current line
prevline = thisline
# Write out the last line, without a trailing newline
if prevline is not None:
write(prevline, lineEnd=stripped)
def encodestring(s, quotetabs=False, header=False):
if b2a_qp is not None:
return b2a_qp(s, quotetabs=quotetabs, header=header)
from io import BytesIO
infp = BytesIO(s)
outfp = BytesIO()
encode(infp, outfp, quotetabs, header)
return outfp.getvalue()
def decode(input, output, header=False):
"""Read 'input', apply quoted-printable decoding, and write to 'output'.
'input' and 'output' are files with readline() and write() methods.
If 'header' is true, decode underscore as space (per RFC 1522)."""
if a2b_qp is not None:
data = input.read()
odata = a2b_qp(data, header=header)
output.write(odata)
return
new = b''
while 1:
line = input.readline()
if not line: break
i, n = 0, len(line)
if n > 0 and line[n-1:n] == b'\n':
partial = 0; n = n-1
# Strip trailing whitespace
while n > 0 and line[n-1:n] in b" \t\r":
n = n-1
else:
partial = 1
while i < n:
c = line[i:i+1]
if c == b'_' and header:
new = new + b' '; i = i+1
elif c != ESCAPE:
new = new + c; i = i+1
elif i+1 == n and not partial:
partial = 1; break
elif i+1 < n and line[i+1] == ESCAPE:
new = new + ESCAPE; i = i+2
elif i+2 < n and ishex(line[i+1:i+2]) and ishex(line[i+2:i+3]):
new = new + bytes((unhex(line[i+1:i+3]),)); i = i+3
else: # Bad escape sequence -- leave it in
new = new + c; i = i+1
if not partial:
output.write(new + b'\n')
new = b''
if new:
output.write(new)
def decodestring(s, header=False):
if a2b_qp is not None:
return a2b_qp(s, header=header)
from io import BytesIO
infp = BytesIO(s)
outfp = BytesIO()
decode(infp, outfp, header=header)
return outfp.getvalue()
# Other helper functions
def ishex(c):
"""Return true if the byte ordinal 'c' is a hexadecimal digit in ASCII."""
assert isinstance(c, bytes)
return b'0' <= c <= b'9' or b'a' <= c <= b'f' or b'A' <= c <= b'F'
def unhex(s):
"""Get the integer value of a hexadecimal number."""
bits = 0
for c in s:
c = bytes((c,))
if b'0' <= c <= b'9':
i = ord('0')
elif b'a' <= c <= b'f':
i = ord('a')-10
elif b'A' <= c <= b'F':
i = ord(b'A')-10
else:
assert False, "non-hex digit "+repr(c)
bits = bits*16 + (ord(c) - i)
return bits
def main():
import sys
import getopt
try:
opts, args = getopt.getopt(sys.argv[1:], 'td')
except getopt.error as msg:
sys.stdout = sys.stderr
print(msg)
print("usage: quopri [-t | -d] [file] ...")
print("-t: quote tabs")
print("-d: decode; default encode")
sys.exit(2)
deco = 0
tabs = 0
for o, a in opts:
if o == '-t': tabs = 1
if o == '-d': deco = 1
if tabs and deco:
sys.stdout = sys.stderr
print("-t and -d are mutually exclusive")
sys.exit(2)
if not args: args = ['-']
sts = 0
for file in args:
if file == '-':
fp = sys.stdin.buffer
else:
try:
fp = open(file, "rb")
except IOError as msg:
sys.stderr.write("%s: can't open (%s)\n" % (file, msg))
sts = 1
continue
try:
if deco:
decode(fp, sys.stdout.buffer)
else:
encode(fp, sys.stdout.buffer, tabs)
finally:
if file != '-':
fp.close()
if sts:
sys.exit(sts)
if __name__ == '__main__':
main()
